Selective electron beam melting of a copper-chrome powder mixture

Additive manufacturing by selective electron beam melting (SEBM) was used to process a powder mixture consisting of elemental copper and chromium powders (nominal composition: Cu-25Cr). The melting temperatures of copper and chromium are largely different. As a result, the copper particles start melting while the chromium ones are still solid. Eventually, also the chromium particles get molten since the local temperatures during SEBM are rather high. The microstructure was analyzed by scanning electron microscopy (SEM) and focused ion beam (FIB)-SEM. It was observed that ultra-fine Cr particles are formed and distributed in the Cu matrix due to the fast cooling rate and subsequent spinodal decomposition.